Although I hate using catchas....
Although I hate having to enter captchas, as a support forum admin I have to implement them.
Before I had captcha on the registration process, the forum was being spammed into oblivion every day. Having email confirmation was next to useless as the spambots could automate it; they would hit the board with hundreds of spams in less than an hour.
It reached the point where I disabled the board entirely, before enabling a rather vicious captcha. Spam still gets in, thanks to the cheap-labour issue mentioned before, but a mere fraction of what used to hit.
I can understand that it makes life difficult for people with visual impairment etc, but the fact is that without it, there would be no forum at all for people to register on as I could not contain the levels of spam. Until something appears that works as well (or better) without the disadvantages, then this is the only option.